1. Field of the Invention
The present invention relates to an ink tank and an ink supply system, and, more specifically, to an ink tank and an ink supply system to be applied to an inkjet printing apparatus.
2. Description of the Related Art
Along the advance of image quality of printing in recent years, commonly employed in inkjet printing apparatuses is a method of increasing the number of ink colors used for printing in order to improve the image quality targeting for photographic image quality. A method of providing multiple tanks is widely used in a desktop printing apparatus, the tanks prepared respectively for different colors and being independently detachable. Such a configuration, however, causes an increase in the number of ink tanks, whereby the frequency of tank replacing operations by a user is increased. Moreover, as the ink tanks are provided independently, the wall thickness of each of the ink tanks has a great influence on the size of the printing apparatus.
Accordingly, from the viewpoint of user friendliness and of downsizing printing apparatuses, ink tanks which are configured to integrate ink containers for multiple colors have been proposed.
In order to achieve stable ink supply, an ink tank of this configuration, i.e. an ink tank provided with multiple ink supply ports corresponding to ink containers for multiple colors, must be attached so that the respective ink supply ports are securely fixed to a holder of the apparatus. To achieve such secure attachment, suggested is an attachment mechanism including a mounting member called a latch lever as disclosed in Japanese Patent Laid-Open No. 10-286972.
FIG. 12 is a perspective view showing an ink tank and a holder for holding this tank on a carriage of an inkjet apparatus disclosed as an embodiment in Japanese Patent Laid Open No. 10-286972. Here, a holder 300 includes an inkjet head 100′ integrally, and is configured to be attached to a carriage of an inkjet printing apparatus and to be detachable therefrom. The inner part of an ink tank 400 is partitioned into six chambers of ink containers. An ink absorber is disposed in each chamber and an ink of each color is impregnated and retained in the ink absorber. Then, six ink supply ports 401 are two-dimensionally arranged in the bottom face of the ink tank 400 so as to correspond to six chambers of the ink containers.
Meanwhile, the holder 300 includes six of chimney-shaped supply pipes (not shown), each having a filter on the tip end thereof, and are disposed in the positions corresponding to the ink supply ports. Moreover, the holder 300 includes retaining holes (not shown) for engaging two claw-like protrusions 405 provided to the ink tank 400, and an engaging hole 321 to be engaged with a latch claw 403 of a latch lever 402 of the ink tank 400.
When attaching the ink tank 400 to the holder 300, the claw-like protrusions 405 are first aligned with and fitted into the retaining holes of the holder 300. Next, the ink tank 400 is rotated pivotally around the fitted section so that the latch claw 403 of the latch lever 402 is engaged with the engaging hole 321 of the holder 300. By attaching the ink tank 400 to the holder 300 in the manner described above, it is possible to cause the filter portions of the supply pipes of the holder 300 to come into contact with the ink absorbers provided to the ink supply ports 401 of the ink tank 400. Accordingly, it is possible to individually supply, to the inkjet head 100′, the six colors of the inks contained in the ink tank 400.
In addition, inkjet printing apparatuses are recently subject to downsizing in order to diversify usages, and products that are small in size yet configured to provide performance equivalent to that of desktop printing apparatuses have been released. A configuration, such as the one disclosed in Japanese Patent Laid-Open No. 2004-249710, of an ink tank that integrates ink containers for multiple colors has been proposed for the application to such a small-sized printing apparatus.
FIG. 13 is a schematic perspective view of the ink tank disclosed in Japanese Patent Laid-Open No. 2004-249710, which is viewed from the bottom face thereof. As similar to the configuration in FIG. 12, the ink tank 10 of this disclosure includes a claw-like protrusion 17 and a latch lever 16 having a latch claw 18 so that the ink tank 10 can be attached to a holder or an inkjet printing apparatus (neither them shown) by an operation similar to the one described with FIG. 12. Ink supply ports 14 for different colors are positioned along a side wall of this ink tank 10, and these ink supply ports 14, the latch claw 18 provided to the latch lever 16, and the protrusion 17 are almost linearly arranged.
In the ink tank 10 having the above-described configuration, it is possible to minimize strength degradation of an enclosure of the ink tank and to prevent deformation of the ink tank by disposing the ink supply ports 14 near the side wall of the tank, i.e. by disposing the ink supply ports 14 in appropriate positions so that rigidity is ensured by the wall face of the ink tank. Moreover, by almost linearly arranging the ink supply ports 14 and the engagement sections with the holder, i.e. by disposing the ink supply ports 14 between the claw-like protrusion 17 and the latch claw 18, it is possible to connect the multiple ink supply ports securely to ink receiving sections provided to the holder.
In recent years, ink tanks for the application to a relatively small-sized inkjet printing apparatus are desired to be able to contain inks having variety in color tones (colors and densities) in order to achieve photographic image quality. Moreover, as the printing speed is remarkably improved in recent years, ink tanks are also desired to have a high efficiency so as to supply ink more stably with a higher flow rate. To meet this demand, an increase in the diameters of ink supply ports has been attempted.
In configuring an ink tank that can meet the demands for diversification in colors and for speeding up, the following problems are likely to occur.
In general, a sealing member made of rubber configured to suppress leakage and evaporation of the ink during attachment of an ink tank is provided in the periphery of an ink supply port or an ink receiving section of the holder to be connected to the ink supply port. For this reason, a reactive force of rubber at the time of attachment becomes greater as the number of ink color tones, i.e. the number of the ink supply ports, increases. Accordingly, the structure configured to simply arrange the ink supply ports two-dimensionally, as disclosed in Japanese Patent Laid-Open No. 10-286972, has a risk of hindering smooth and secure attachment of the ink tank (degradation in the attachment property). Moreover, this structure also has a risk of hindering secure connection between the ink supply port and the ink receiving section (degradation in connectivity).
Meanwhile, the structure configured to arrange the ink supply ports linearly (Japanese Patent Laid-Open No. 2004-249710) incurs an increase in the number of ink color tones, i.e. an increase in the number of the ink supply ports and in the diameter of the ink supply ports associated with speeding up in ink supply, which leads to an increase in length of the ink tank in the direction of the arrangement of the ink supply ports, and thus hinders downsizing of the ink tank.